1. Field of the Invention
The present invention relates to playback of multimedia content. More particularly, the present invention relates to a method and apparatus for seeking a target frame from among all frames included in multimedia content.
2. Description of the Related Art
As portable multimedia playback devices have been developed and their performance has improved, portable consumption of large capacity multimedia content having a high bitrate, such as high definition video, lossless audio, and other similar large capacity media and multimedia content has increased.
Codecs may adopt a variable bitrate that allows encoding of multimedia data based on a characteristic of a frame, so as to provide a maximum compression rate and to secure a high quality for each frame of the large capacity multimedia content having a high bitrate, for example, a high definition video quality, a high sound quality, and the like.
However, when the multimedia data is encoded based on the variable bitrate, a bitrate of a frame is not fixed. Accordingly, to move to, i.e., determine or select, a predetermined position of multimedia content including frames having variable bitrates, all the frames up to the predetermined position may need to be parsed. This scheme may be referred to as a pre-rolling scheme that parses frames from a first frame up to a frame located at a desired point when performing seeking of the frame at the predetermined position. Although the pre-rolling scheme is readily embodied, the data parsed during seeking is discarded and thus, parsing is performed from the first frame every time it performs seeking. Accordingly, the pre-rolling scheme is inefficient and performance may be deteriorated in a case where a desired point is distant from the first frame.
In order to overcome the above noted drawback, a scheme that generates a seek table by parsing all the frames before decoding or a scheme that generates a seek table and inserts the generated seek table into a file format during encoding, may be used. However, due to the increase in large capacity multimedia content, the scheme based on the seek table may include problems, such as a slow seek time, use of a large amount of memory, a low accuracy in seeking a result, and the like.
According to the scheme for generating a seek table before decoding so as to reduce overhead from the scheme of parsing all the frames, all the frames may need to be parsed and the seek table may need to be initialized before decoding. The initialization of the seek table may cause a large amount of initial playback delay during decoding, and the initial playback delay may increase as a quantity of content and a length of playback time increase.
According to the scheme of generating a seek table and inserting the seek table into a file format during encoding so as to remove overhead occurring while generating the seek table during a decoding operation, a compression rate of an encoder may be deteriorated and thus, a limited number of seek tables may be generated. Accordingly, the seek table may have a low accuracy and thus, a result of a seeking operation using the seek table may be inaccurate. Also, an accuracy may be deteriorate as a playback time increases. In addition, when a seek table is deleted or damaged during storing or streaming, seeking performed based on the seek table may not be able to be carried out.